ESTRO 2022 - Abstract Book

S654

Abstract book

ESTRO 2022

Conclusion These results suggest that a tattoo-less setup approach with AlignRT (ART) may be sufficiently accurate to supplant surface tattoos for patients receiving APBI. Further analyses with larger cohorts will determine whether tattoo-based (TTB) approaches can be replaced by surface imaging.

PD-0742 Implications of heart contractility on the dose to the LAD in DIBH radiotherapy for breast cancer

M.N. Duma 1 , S. Völkel-Beltran 2 , L. Pargmann 2 , P. Schlattmann 3 , A. Wittig 2

1 University Hospital Jena, Department of Radiotherapy and Radiation Oncology, Jena, Germany; 2 University Hospital Jena, Department of Radiotherapy and Radiation Oncology , Jena, Germany; 3 University Hospital Jena, Institute for Medical Statistics, Computer Science and Data Science (IMSID), Jena, Germany Purpose or Objective Larger studies on the impact of heart contractility during deep inspiration breath hold (DIBH) for letfsided breast cancer

are lacking. The aim of this study is to assess the dosimetric impact of cardiac contractility on the left anterior descending

artery (LAD) during whole breast irradiation (WBI) in DIBH for leftsided breast cancer.

Materials and Methods 73 patients were included in this study with free breathing (FB) and DIBH scans. The treatment planning was performed in a 3D-conformal tangential field treatment technique on the DIBH in the RayStation (V.8, RaySearch Laboratories, Stockholm, Sweden). To reduce interobserver variability in CTV definitions and treatment approaches, retrospectively the contouring of the CTV (CTV+1cm=PTV) and dosimetry were performed by the same two observers (LP and SVB) respectively. A movement of the LAD-as described by MRI studies on DIBH breast cancer radiotherapy-of 0.27cm in the LR direction, 0.41cm in the SI direction and 0.24cm in the AP direction was simulated using deformable image strategies. 4D- CTs with 6 phases each were generated for each patient. All treatment plans were primarily calculated on the “static” DIBH planning CT (P-CT) and were recalculated on each of the 6 phases of the 4D-CTs (Fig.1).